A railway freight car is comprised of a car body and two three piece freight trucks. Two center plates are also provided, which are centrally attached and located near the ends of the car body. The center plate is a casting that extends from the car body into a center bowl of the bolster of the three piece freight truck. The three piece freight truck consists of a bolster and two side frames. The vertical weight of the car body is transferred from the bottom of the centerplate to the mating surface of the truck bolster center bowl. Two sidebearings also transfer the loaded weight of the car body to the bolster. The car body weight is then transferred from the bolster through the suspension, into the side frames, and finally through the axles and wheelset, continuing onto the track. The bolster center bowl has a circular vertical wall that captures the center plate lower section circular vertical wall. The circular interface restricts the movement of the center plate to only rotation of the three piece freight truck relative to the car body. The vertical walls between the center bowl and the center plate have a radial space to allow for assembly clearance.
The stability of the railway freight car is a function of track irregularities and mass acceleration, created by the speed of travel. The track irregularities and the speed of travel tend to laterally displace and accelerate the mass of the three piece freight trucks. The laterally displaced and accelerated mass at the bolster center bowl circular vertical wall travels through the radial clearance space impacting the car body center plate lower section vertical circular wall. The impact transfers the lateral displacement and accelerated mass energy into the car body where it is momentarily stored. When the car body restores to equilibrium it returns the displaced mass and energy back through the vertical wall of the center plate, traveling through the radial clearance space and impacting the center bowl of the three piece freight truck. The cycling of displacement of energy causes the railway freight car to become unstable.
The present invention relates to absorbing the displacement energy from the bolster center bowl circular vertical wall to the car body center plate circular vertical wall. Radially preloaded spring elements, placed between the circular walls of the bolster center bowl and car body center plate lower section circular vertical wall, eliminate the impact and absorb the displacement energy being transferred between the three piece truck and car body. Absorbing the displacement energy between the car body and three piece truck, allows increased speed of travel while maintaining the stability of the railway freight car.